KANSAS CITY, Mo. (AP) — The Chiefs put tight end Kevin Boss on injured reserve with a head injury Wednesday after doctors determined they would not clear him to play the rest of the year.

Boss signed a $9 million, three-year deal in the offseason to provide a versatile tight end for quarterback Matt Cassel, and insurance with Tony Moeaki coming off a torn left ACL.

He caught three passes for 65 yards and a touchdown before getting hurt in Week 2 at Buffalo, when Bills safety D'Norris Searcy's elbow slammed into his helmet.

"When he didn't make the comeback, you know, and it was taking time, I was kind of concerned there might be an issue, because generally they do those baseline tests and you can make a comeback, you see improvement," Chiefs coach Romeo Crennel said. "So when it took a little longer to show improvement, I thought there could be an issue, and found out there was one."

The injury is a significant blow to a Chiefs offense that has struggled with inconsistency, leads the league in turnovers and has been unable to put together many sustained drives.

Boss, who carved out his reputation with the New York Giants, caught 28 passes for 368 yards and three touchdowns with the AFC West-rival Oakland Raiders last season.

"Kevin was disappointed. We were disappointed, because we thought he was a good addition to the team, thought he'd be able to help us," Crennel said. "He enjoys playing football, wants to play football, but with his situation, he won't be able to pay this year."

Crennel said recent emphasis on player safety, in particular when it comes to concussions, only underscored the decision to shut Boss down for the season.

A federal lawsuit was filed in Mississippi in August on behalf of more than 50 former NFL players who claim the league conspired to hide the dangers of brain trauma associated with playing professional football. More than 140 similar lawsuits have been filed around the country.

"I think the doctors, they do their job," Crennel said. "They look at all the things and make the decision, and in their determination, they decided not to let him play again."

Crennel said that the Chiefs had signed linebacker Bryan Kehl, who spent last season with the St. Louis Rams, to fill the roster spot opened up by putting Boss on injured reserve.

The decision to add depth at linebacker rather than another tight end indicates that Crennel believes Moeaki is healthy enough to carry a full load, and that backups Jake O'Connell and Steve Maneri — a former offensive lineman — are capable of making a positive contribution.

In other news, the Chiefs were forced to practice for Sunday's game against Baltimore without running back Peyton Hill (right ankle), defensive ends Glen Dorsey (left calf) and Ropati Pitoitua (left elbow), and cornerback Jalil Brown (hamstring) on Wednesday.

Page 2 of 2 - Linebacker Derrick Johnson, offensive lineman Ryan Lilja and safety Kendrick Lewis were among several starters who were limited because of various injuries.

"The guys who can practice will practice, and the guys who are limited will be limited," Crennel said, "and we'll go from there."